View Full Version : KM C6000: RGB images too dark (but fine in IV)

09-11-2013, 01:44 AM

I'm trying to figure out what I'm doing wrong: I have a simple PDF file (which was converted out of MS Word by a customer). There is only black text and a small photo on the page.

Using Acrobat, the photo looks quite okay (and bright) on my monitor. Then I import and rip the file on my KM C6000 (IC-306v2) and take a look using Image Viewer. There the photo looks a little bit different (as expected) but still fine and bright enough.

But if I print the job, the photo is really dark and many details were simply invisible because they are nearly black.

I can't understand why this happens. The printer is equipped with an inline spectrometer (RU-509) and we are using a custom media profile which was created exclusively for our printer and media at the time of installation.

Our displays are all calibrated and the corresponding profiles are set in Image Viewer. The Fiery itself is set to use FOGRA39L (Output-GCR) / sRGB (relative colorimetric) source profile and to respect embedded profiles.

Is there anything else I can try? I don't believe it's a machine fault but I might be wrong :rolleyes:

09-11-2013, 09:55 AM
I suggest you enable the control bar feature if you have the Graphic Arts Package Premium Edition - and enable the reporting options to inspect the output profile and calibration being applied to the job. This will help you to determine if you have applied the custom output profile, and which calibration data is being used.

09-11-2013, 05:18 PM
Thanks for your answer. The report just tells me the (expected) settings I've already done in the job properties: The entire page consists of RGB objects which were rendered using the sRGB profile. My output profile is applied (as it should because it's my default setting).

09-11-2013, 08:20 PM
What about calibration?

09-11-2013, 10:35 PM
I calibrate the printer only once a month using an ES-2000 because the inline spectrometer does quite a good job in (re-)linearization: If I compare the measured values with the target values there's almost a perfect match.

My problem is that our old DocuColor 252 shows the same behaviour but there I'll print the jobs using Acrobat instead of submitting the PDFs directly.

I haven't been able to track it down to specific input files because it happens on Word-PDFs as well as on files exported from Apple's photo calendar app.

The only way, image brightness prints fine is when customers send me PDFs created out of Adobe applications like InDesign or Illustrator. So I guess it has something to do with the color space.

But this still doesn't explain why everything looks fine in Image Viewer (which should do some kind of softproofing, shouldn't it?).

09-16-2013, 09:17 AM
Image viewer uses the Monitor Profile and the job's Output profile to soft proof the CMYK values in the raster. As you have determined that the output profile is the correct one - I suggest you confirm that the monitor profile is also correct before you rely on Image viewer for you assessment of the correctness of the raster.

That being said - Image Viewer has no awareness of the correction curves being applied in Calibration - and it can only preview output assuming the Output profile is perfect.

At this point - I would suspect a calibration related issue. Clibration may not be in the same state that the profile was in when it was created. Possibly calibration is being applied twice?

Best practice is to pick one place to perform calibration and ensure the curve applied by the other system never changes.

09-16-2013, 10:34 PM
Thanks for your answer. Yes, I am aware of the monitor profiles and therefore I have tested it using three different systems: Two of them have calibrated displays (using EFI's CPS) and one is uncalibrated. The colors in IV are slightly different (especially on the uncalibrated display) but the brightness is okay on all of them.

The output profile of the C6000 should be okay. It was created at the time the machine was installed at my site (nine months ago) and if verify it using CPS, I get an almost perfect match (deltaE against the output profile is < 3).

A technician recently did a complete "refresh" (exhanging all drums and several other parts) and the "curves" after an afterwards linearization showed a quite good match.

I can also sort out any "double color correction" issues because I submit the PDFs directly using CWS.

09-17-2013, 07:56 AM
All too frequently, Fiery calibration can go corrupt--and a simple re-calibration *won't* fix that.

My go-to for things like this is to go into Calibrator and "Restore Device". This gets rid of everything and goes back to factory defaults.

Then calibrate as usual.

09-17-2013, 08:21 AM
Yes, my KM technician also told me to do so (but also told me that I don't need to re-calibrate daily as I did on older machines). And I've also checked the option "machine calibration" as well as printing ten sheets of calibration pages in order to let the machine "warm up" ...